Graphic: The rise of Somali piracy

Piracy attacks on the world’s shipping rose by a third in the first half of this year and became increasingly violent, with pirates using machineguns, grenade launchers and other weapons, the International Maritime Bureau said on Thursday.

Worldwide attacks rose to 266 in the first six months of 2011 compared with 196 in the same period last year. More than 60% were by Somali pirates.

Here are details of ships still held by Somali pirates.

• SOCOTRA 1: Seized on Dec. 25, 2009, in the Gulf of Aden. The Yemeni-owned ship had six Yemeni crew.

• CHOIZIL: Seized on Oct. 26. South African-owned yacht hijacked after leaving Dar es Salaam. European Union anti-piracy task force rescued one South African but two other crew members were taken ashore and held as hostages.

• ORNA: Seized on Dec. 20. The Panama-flagged bulk cargo vessel, 27,915 dwt, owned by the United Arab Emirates, was seized 400 miles northeast of the Seychelles.

• SHIUH FU NO 1: Seized Dec. 25. Somali pirates appeared to have seized the Taiwanese-owned fishing vessel near the northeast tip of Madagascar in the Indian Ocean. The vessel had a crew of 26 Taiwanese, Chinese and Vietnamese nationals.

• BLIDA: Seized on Jan. 1, 2011. The 20,586-tonne Algerian-flagged bulk carrier was seized about 150 miles southeast of Salalah, Oman. The ship, with 27 crew from Algeria, Ukraine and the Philippines, was heading to Dar es Salaam, Tanzania, from Salalah with a cargo of clinker.

• HOANG SON SUN: Seized on Jan. 19. The 22,835-tonne bulk carrier, which is Mongolian flagged and Vietnamese-owned and has a crew of 24 Vietnamese nationals, was seized about 520 nautical miles southeast of the port of Muscat.

• SAVINA CAYLYN: Seized on Feb. 8. The 104,255-dwt tanker, Italian-flagged and owned, was on passage to Malaysia from Sudan when it was attacked 670 miles east of Socotra Island. It had five Italians and 17 Indians on board.

• SININ: Seized on Feb. 12. The Maltese owned and registered bulk carrier was seized with a crew of 13 Iranian and 10 Indian nationals in the North Arabian Sea. The 53,000 dwt vessel was on route to Singapore from Fujairah in the United Arab Emirates.

• ALFARDOUS: Seized on Feb. 13. The Yemeni fishing vessel was believed to have been pirated close to Socotra Island in the Gulf of Aden and has a crew of eight

.• DOVER: Seized on Feb. 28. It was taken about 260 nautical miles northeast of Salalah in Oman. The Panamanian flagged, Greek owned vessel was on its way to Saleef (Yemen) from Port Quasim (Pakistan) when it was attacked. The crew consists of three Romanians, one Russian and 19 Filipinos.

• SINAR KINDUS: Seized on March 16. The Indonesian flagged and owned bulk cargo carrier was taken approximately 320 miles northeast of Socotra in the Somali Basin. The ship, with 20 crew, was quickly used to launch further attacks.

• ROSALIA D’AMATO: Seized on April 21. The Italian-owned bulk carrier was captured 560 km off the coast of Oman. The 74,500 tonne bulk carrier was on its way to Bandar Imam Khomeini in Iran from Brazil with a cargo of soya. The 21-person crew consisted of six Italians and 15 Filipinos.

• GEMINI: Seized April 30. The Singapore-flagged chemical tanker was seized off the Tanzanian coast, 115 miles east of Zanzibar. The 29,871 dwt vessel carried 28,000 metric tonnes of crude palm oil from Kuala Tanjung in Indonesia to Mombasa in Kenya. The 25 crew consist of four from South Korea, 13 from Indonesia, three from Myanmar and five from China.